It is ITV's most-watched new drama since Scott and Bailey launched in 2011.

Steve November, ITV's acting director of drama commissioning, said: "It is ITV drama at its best and we are looking forward to spending more time with the wonderful characters."

The director of episodes 5, 6 and 7 of series one, Anthony Byrne (Silent Witness, Single Handed), will return to direct the first of the new episodes.

Kate Lewis, exec producer for ITV Studios, said: "ITV Studios is thrilled to be making a second series of Mr Selfridge. The story of Harry Selfridge, his family and colleagues has drawn in a strong drama audience and we are delighted by the response. The second series will allow us to build on this success and it is a fantastic opportunity to focus on 1914 during the centenary of the Great War."